The prosecution of crimes is the responsibility of the Public Prosecutor's Office and the judicial police, which is under the authority and immediate orders of the Public Prosecutor's Office, and since this is a constitutional guarantee providing that accused persons must be tried by justices not belonging to the judicial police, which is subordinate to the Public Prosecutor's Office, this guarantee would be denied if the justices were subordinate to the Public Prosecutor's Office and thus became both judges and parties, responsible for deciding whether the accused person was criminally responsible and for presenting ex officio the necessary evidence on which to base the charge. Hence the Public Prosecutor's Office must be involved from the outset of the investigation onwards, because the constitutional guarantee at issue requires the courts to be entirely impervious to influence, and they would be influenced, prejudicially, if they were obliged and empowered to assemble evidence against the accused.
La persecución de los delitos incumbe al ministerio público y a la policía judicial, la que estará bajo la autoridad y mando inmediato de aquel, y siendo ésta una garantía constitucional, consistente en que los reos deben ser juzgados por jueces que no pertenezcan a la policía judicial, que está subordinada al ministerio público, resultaría negatoria dicha garantía, si los jueces estuvieran subordinados al ministerio público; convirtiéndose así en jueces y parte, encargados al mismo tiempo de decidir sobre la responsabilidad penal del inculpado y de allegar de oficio los elementos necesarios para fundar el cargo; por esto es indispensable la intervención del ministerio público, desde el principio de la averiguación, porque la garantía constitucional de que se trata, exige que el juez esté totalmente libre de la influencia moral, que se establecería en él, en forma de perjuicio, si tuviera la obligación y la facultad de reunir los elementos de prueba en contra del inculpado.